Hearing can serve as an early warning system because it can panoramically monitor the environment for events happening at a distance or out of sight. These ecological considerations make the auditory system particularly useful for studying mechanisms for shifting spatial attention. The focus of this project is on the interplay between top-down and bottom-up spatial attention biases that govern shifting auditory attention to distractors during performance of a simple spatial attention task. The overall goal of this proposal is to use an interdisciplinary approach to better understand at the cognitive and neural levels of analysis how auditory attention is distributed over space. We will test the hypothesis that the spatial distribution of auditory attentional emerges from interactions among two basic factors. The first factor is a voluntary (top-down) attention bias that weakens with distance from the current focus of attention. Conversely, the second factor is an automatic (bottom-up) bias that is tuned to shift attention to unexpected events away from the current focus of attention. The first aim tests a computational model of top-down and bottom-up attention bias in shifting auditory spatial attention. Different aspects of the model will be quantitatively tested against findings from behavioral experiments, and observations will be used to further develop the model. The computational model will incorporate artificial intelligence methods to represent human cognitive processes. The second aim uses transcranial magnetic stimulation to test the role of key right hemisphere cortical areas in shifting of auditory spatial attention. We focus on neural mechanisms of bottom-up attentional bias. The third aim tests whether auditory attention gradients become less focused over time. This will determine how gradients relate to cognitive resources and neural blood flow measures that are known to decline with extended vigilance. This project will help advance knowledge in the field of auditory attention and cognitive hearing, and also addresses general issues in attention research such as top-down and bottom-up processes, vigilance, and their relations to neurobiological attention networks. Outcomes will have practical significance because shifting auditory attention is vital for avoiding accidents at ll ages, maintaining independent living at older ages, and is applicable to neurological and psychiatric disorders having attentional impairments (e.g. PTSD, attention deficit disorder, schizophrenia, stroke, dementia).